During an intravascular procedure, it is typically necessary to utilize some type of mechanical device to remove an occlusion from a vessel. Generally a recanalization catheter including a rotatable working head with a fixed diameter is used for engaging and cutting the blockage from the vessel wall. As the catheter is advanced, the vessel increases or decreases in diameter necessitating the use of several different tip sizes to complete the procedure. Fixed diameter catheters of this type are available from Dow Corning Wright-Theratek, under the name "TRAC-WRIGHT", in various size designations.
To change the working diameter during the procedure, the catheter is removed from the lumen of the vessel and a catheter having a larger or smaller working diameter corresponding to the changed lumen diameter is reinserted into the vessel.
U.S. Pat. No. 4,895,560 to Papantonakos describes a milling tool for angioplasty comprising an actuator cylinder for increasing or decreasing the diameter of the tool. The tool further comprises a multiplicity of flexible, leaf-shaped flutes axially connected to a driving rod. The flutes are linearly displaceable with respect to the actuator cylinder, causing a change in the radial dimension of the flutes. As the rod is retracted by the actuator through a base plate the tool is compressed, forcing the flutes to bow outward thereby increasing the effective working diameter of the tool a corresponding amount. One disadvantage of this tool is that sharpened edges of the rotating flutes can damage vascular tissue.
U.S. Pat. No. 4,811,735 to Nash describes a catheter for destroying gallstones within the body. The catheter is positioned adjacent a stone to pulverize it on contact when the working head is rotated. The working head comprises several pivotally mounted impacting arms radially arrayed at the end of a drive shaft that is said to rotate at high speeds from 5,000 to 100,000 rpm. The centrifugal force of rotation urges the pivotally attached arms to move from a retracted position to an extended position, thus striking the stone and disintegrating it. The catheter utilizes centrifugal force to cause the hammers to pulverize the stones, rather than scraping to remove occlusions from a vessel.
Accordingly, there remains a need for a rotating catheter which is expandable to different working diameters and non-cutting to vascular tissue having varying lumen sizes.